As part of my undergrad I shadowed dozens of physicians in varying specialties and never had a problem. One of my last rotations was following an Orthopedic Intern in the ED in the middle of the night. Dozens of students in my program have done it with no problem whatsoever.
Everything was going great, I got to help on a few procedures, see a ton of different patients, and watch a few bullets being removed in surgery. That was until a LOL came in with a displaced radius that needed to be relocated.
It's a simple enough procedure that basically entails wrenching the radius back into position after the whole wrist is relaxed. I thought it would be nice and quick like the shoulder and patella relocations I have seen/done myself and relatively painless because she was on a ton of painkillers.
So the Ortho Intern starts going at it while his resident watches and I stand on the other side of the bed. It becomes quite apparent this isn't going to be quick or easy because as soon as the Intern starts manipulating the radius I can hear bone scrapping against bone and then the LOL starts howling in pain. This goes on for a good 5 min.
Then I learned I have an aversion to people screaming in pain or more specifically people who cause someone else to scream in pain. Just as realize I'm not feeling so great and need to leave the room, I pass out. Apparently on the way down I also took the cabinet out too.
I came to a few seconds later and was so pissed off/embarrassed that I immediately tried to stand up and pretend it didn't happen, but couldn't because 3 nurses were trying to cover the huge gash I had on my head.
Apparently my wound was the coolest thing going on in the ED at the time because for the next 2.5 hours while I got 30+ sutures put into my head, I swear every single nurse/doctor/med student in both the adult and pediatric EDs came by to look at it.
Now I'm very well known by all the Emergency, Orthopedic, and Sports Medicine attendings at a large teaching hospital because of this...and not necessarily by name, but they definitely recognize me by my scar (which is barely viable unless you are looking for it).
And small side note:
The LOL came in with her son, who was in the room when I keeled over. He happened to show up at a completely different clinic a year later on the exact same day I was shadowing General Practitioners there. I got to watch his rectal exam because he felt that we had a bond.